Android Input输入系统之四:KeyEvent事件中的InputChannel通信
Android Input输入系统之一:KeyEvent事件监听及事件分发流程
Android Input输入系统之二:KeyEvent注入事件及事件分发流程
Android Input输入系统之三:KeyEvent事件分发和上层应用层对事件的接收
Android Input输入系统之四:KeyEvent事件中的InputChannel通信
经过一系列的分析,key事件的分发,中间有一个InputChannel通信。
key事件发送端,InputDispatcher,属于system_server进程;
key事件接收端,ViewRootImpl,是应用程序进程。
这两者之间的跨进程通信就是通过InputChannel实现的。
重点还是看一下InputChannel的创建过程。
/** A window in the window manager. */
public class WindowState extends WindowContainer<WindowState> implements WindowManagerPolicy.WindowState {
void openInputChannel(InputChannel outInputChannel) {
if (mInputChannel != null) {
throw new IllegalStateException("Window already has an input channel.");
}
String name = getName();
InputChannel[] inputChannels = InputChannel.openInputChannelPair(name);
mInputChannel = inputChannels[0];
mClientChannel = inputChannels[1];
mInputWindowHandle.inputChannel = inputChannels[0];
if (outInputChannel != null) {
mClientChannel.transferTo(outInputChannel);
mClientChannel.dispose();
mClientChannel = null;
} else {
// If the window died visible, we setup a dummy input channel, so that taps
// can still detected by input monitor channel, and we can relaunch the app.
// Create dummy event receiver that simply reports all events as handled.
mDeadWindowEventReceiver = new DeadWindowEventReceiver(mClientChannel);
}
mService.mInputManager.registerInputChannel(mInputChannel, mInputWindowHandle);
}
@Override
String getName() {
return Integer.toHexString(System.identityHashCode(this))
+ " " + getWindowTag();
}
CharSequence getWindowTag() {
CharSequence tag = mAttrs.getTitle();
if (tag == null || tag.length() <= 0) {
tag = mAttrs.packageName;
}
return tag;
}
}
name是window的title名或者包名。
InputChannel[] inputChannels = InputChannel.openInputChannelPair(name);
openInputChannelPair(),创建了一对InputChannel分别是mInputChannel和mClientChannel,mInputChannel是服务端的channel,mClientChannel是客户端的channel。
通过mClientChannel.transferTo(outInputChannel);将mClientChannel传递给View应用端的outInputChannel中。即将fd传给客户端。
通过registerInputChannel将mInputChannel注册到InputDispatcher中。
mService.mInputManager.registerInputChannel(mInputChannel, mInputWindowHandle);
这样就分别创建了一对服务端和客户端的InputChannel,并分别把fd传给服务端和客户端。
建立起了InputDispatcher的View之间的联系。
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